Today’s Secret Science Society episode is dedicated to every scientist who is also an artist – which means most of them! While scientists have created art as unusual as cosmic symphonies and as amusing as hidden images. There have been many famous scientists who were also artists and many famous artists who were also scientists. This week, Daniel, Mary, and Peter join their ranks as they discover the art of science!
Mary, Peter and Daniel were just like any other kids. They liked school, but they really enjoyed going on field trips. Sometimes they went to the university and saw the experiments that were being done. Sometimes they went to the nature preserve and watched animals. But today, their class had gone to the art museum. Though they weren’t too sure that they would like it, they were having a great time as they looked at the different works of art and tried to see the science in them.
“Wow!” Peter exclaimed. “Look at how the lines in the pavement in that painting converge.”
“Mr. Medes told Daniel and me about that last week,” Mary said proudly. “It is called perspective, and it was invented by a painter who was also a mathematician. It makes things look really real in paintings. His name was Pruney-something.”
“Brunellesci,” Daniel corrected. “It was a weird name so I wrote it down.”
“That’s neat. I wonder if artists used any science other than math?” Peter said.
“Well, they probably had to know chemistry in order to make their paints,” Daniel replied. “And some of them knew a lot of geology; Mr. Medes told us about the rocks in Leonardo da Vinci’s paintings, remember?”
“That’s right; I forgot,” Peter admitted sheepishly. Just then, the three turned the corner into the modern art section of the museum. “Hey! That is so cool!”
Hanging from the ceiling in front of the three friends was a giant sculpture made of many smaller pieces that slowly rotated as they revolved around each other. Mary bent to look at the tag with the name of the art work.
“Vertical foliage by Alexander Calder, on loan from private collection” she read out. “It does look like leaves swirling around.”
“I wonder how he managed to get that to work?” Daniel asked.
“Nothing but a little applied physics,” Mary’s father said.
“What do you mean, dad?” replied Mary.
“It is an admittedly beautiful example of physics in action. Calder used the center of mass to make sure that the sculpture was balanced and then hung it all up so that it could be moved by the air.”
“Center of mass?” Peter asked. “What’s that?”
“Well, to understand that, all you need is two hands and a ruler like this one,” Mary’s father replied after rummaging in his backpack for a moment. “Daniel, stick your hands out about seven inches apart. Now make a fist, but point out with your pointer finger on each hand. Hold your hands level, because I’m going to put this ruler on them and I don’t want it to fall off.”
Looking interested, Daniel complied with his directions. Just as soon as Daniel’s fingers were level, Mary’s father put the ruler on top of them with the one inch mark on top of the left finger and the eight inch mark over the right one.
“OK, now we’re ready. We can all agree that the middle of a ruler is at the six inch mark, right?” Seeing their nods, Mary’s father continued. “Now Daniel is going to slowly move his fingers together. What do you think will happen?”
“The ruler will fall off,” Daniel said promptly. “My fingers will meet at four and a half inches, and the ruler will fall.”
“I don’t know,” Peter said. “Maybe the ruler will stay on somehow.”
Mary disagreed with Peter. “I think that Daniel is right; the ruler will fall.”
“OK,” Mary’s father said. “Let’s find out! Daniel, start slowly moving your fingers together!”
What do you think will happen? Do the experiment!
Mary and Peter watched as Daniel moved his finger together. At the start, the ruler moved with his right hand and slid toward the left. Then it started to move with the other hand and alternated until Daniel’s fingers met at the six inch mark.
“Hey! You cheated!” Mary said. “It should have fallen!”
“OK, you try it!” Daniel challenged.
Mary put the ruler on her fingers, just as they had been on Daniel’s. She then started to move her fingers together. Again the ruler eerily moved with one hand then the other until her fingers met at the middle.
“What’s going on?” Mary asked.
“Daniel and you just found the center of mass of the ruler,” her father said. “When you put the ruler off-center the way that we did, there’s more mass on one side so there’s more weight on the finger on that side. That increases the friction so that the ruler is ‘stuck’ on that finger until the weight is evenly distributed. Where your fingers meet is the place where you could crush all of the mass and still have everything balance. Physicists call that the center of mass, unless they are really old physicists. Then they call it the center of gravity.”
“How does that make the sculpture work?” Daniel asked.
“Every object has a center of mass. If you hang it from that point, the object can turn and move freely. So what Calder did was find the center of mass for each leaf and then put a wire through it. He then arranged the leaves so that the center of mass for the whole bunch passes through that point there” Mary’s father pointed at the center wire of the sculpture. “That put the entire sculpture in such good balance that just a breeze can make it move. Because his sculptures can move by themselves, Calder called them mobiles.”
“Neat!” Peter said. “How about we make a mobile of our own when we get home?”
Daniel and Mary just nodded, as they watched the mobile slowly moving in the breeze.